JP2006319224A - White light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good white light while maintaining luminous efficiency.
An LED element that emits blue light is mounted on a substrate. A sealing resin 3 which is a YAG phosphor encapsulating resin is sealed around the LED element 1. A condensing lens 4 is disposed in the light emitting direction of the LED element 1. A light diffusing agent 5 is mixed in the lens 4. The white LED 10 combining the blue light emitting LED element 1 and the YAG phosphor obtains white light by mixing the blue light from the LED element 1 and the yellow light obtained by exciting the YAG phosphor with the blue light. .
[Selection] Figure 1

Description

  The present invention relates to a white light-emitting diode used for a general illumination light source, an automobile headlight, and the like.

In recent years, a white light emitting diode (hereinafter abbreviated as white LED) has been developed by combining a blue LED and a YAG phosphor, and is used as a next-generation energy-saving illumination light source. FIG. 2 is a cross-sectional view showing a conventional white LED. In FIG. 2, 50 indicates a white LED. Reference numeral 1 denotes an LED element that emits blue light, and reference numeral 2 denotes a substrate on which the LED element 1 is mounted. Reference numeral 3 denotes a sealing portion in which the LED element 1 is sealed with a YAG phosphor encapsulating resin. Reference numeral 54 denotes a condensing lens disposed in the light emitting direction of the LED element 1. The white LED 50 combining the blue light emitting LED element 1 and the YAG phosphor obtains white light by mixing the blue light from the LED element 1 and the yellow light obtained by exciting the YAG phosphor with the blue light. . In order to obtain good white light, it is necessary to mix these two colors without unevenness. Generally, this can be achieved by mixing a light diffusing agent consisting of transparent fine particles such as glass powder in the phosphor-encapsulating resin. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).
Japanese Utility Model Publication No. 59-050455 (FIG. 3, pages 4-7) Japanese Patent Laid-Open No. 06-296043 (FIG. 6, paragraph number 0008) Japanese Patent Laying-Open No. 2004-274087 (FIG. 1, paragraph number 0027)

  However, when a lens is installed in front of the LED element to obtain white light having a certain degree of directivity, color separation (halo effect) occurs in the irradiated light. This is white light obtained by the complementary color relationship between the blue light and the yellow light obtained by exciting the YAG phosphor with the blue light. Therefore, even if an image is formed at one point with monochromatic light, white light is obtained. In some cases, however, images with different focus depending on the wavelength are superimposed, and the image may be blurred or the edges may be colored. This is because the refractive index of glass or plastic changes (disperses) according to the wavelength, and when white light is incident on the lens, the focal length varies depending on the wavelength, and directs the irradiated light through the lens. And color separation appears even more prominently.

  The present invention has been made to solve such a conventional problem, and an object of the invention is to provide a white LED capable of preventing both the halo effect and a decrease in light transmittance.

  The means of the present invention for solving the above-described problem is a white light emission comprising a light emitting diode that obtains white light from a mixed color of light of a plurality of wavelengths, and a condensing lens disposed in the light emitting direction of the light emitting diode. The diode is characterized in that a light diffusing agent is evenly dispersed in the lens and mixed to a weight ratio of several percent or less to provide a halo effect reducing function.

  Further, the lens is an achromatic lens.

  In addition, the lens and the sealing portion are formed separately.

  The light of the plurality of wavelengths includes blue light of a light emitting diode element that emits blue light and yellow light from a YAG phosphor excited by the blue light.

  According to the present invention, in a white light emitting diode comprising a light emitting diode that obtains white light from a color mixture of a plurality of wavelengths and a condensing lens disposed in the light emitting direction of the light emitting diode, light diffusion is performed in the lens. Since the halo effect reducing function was provided by mixing several percent or less of the agent, the reduction of the halo effect and the maintenance of light transmittance could be realized at the same time, and good white light could be obtained. The white light emitting LED is in a stage where the quality of white light as well as the amount of light is asked, and the industrial value of the present invention is high.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of a white LED that is an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a white LED according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a white LED that obtains white light from a mixture of light of a plurality of wavelengths. The light of the plurality of wavelengths includes blue light of a light emitting diode element that emits blue light, and the blue light. And yellow light from the YAG phosphor excited by. Reference numeral 4 denotes a resin lens for condensing light, which is formed separately from the sealing portion 3. The lens 4 may be an achromatic lens. The lens 4 is bonded to the sealing portion 3 with an adhesive, or is bonded to the sealing portion 3 simultaneously with the curing of the sealing resin. Reference numeral 5 denotes a light diffusing agent that is evenly dispersed in the lens 4 and mixed in a weight ratio of several percent or less. The light diffusing agent is also mixed in the sealing resin of the sealing portion 3. The amount of light diffusing agent in the lens 4 is smaller. Since other configurations are the same as those of the conventional white LED 50, the same reference numerals and names are assigned to the same components, and detailed description thereof is omitted.

  Next, the effect of the white light emitting LED which is embodiment of this invention is demonstrated. Instead of increasing the light diffusing agent concentration in the sealing resin, the light diffusing agent 5 is mixed in the lens 4 by several percent by weight or less so that the concentration of the light diffusing agent in the sealing resin can be low. For this reason, the light transmittance is not lowered, and the diffused light generally tends to be emitted outside the package. Using a light diffusing agent to reduce the halo effect in the irradiated light is an effective method, but at that time, rather than increasing the concentration of the light diffusing agent in the phosphor encapsulating resin, a light diffusing agent is added to the lens. As a result, the halo effect can be reduced while suppressing a decrease in light transmittance. By making the lens 4 an achromatic lens, the halo effect can be further reduced. Since the lens 4 and the sealing portion 3 are made separately, they can be made without any problem even if the concentration of the light diffusing agent is different.

  The white LED of the present invention is widely applied as a general illumination light source, an automobile headlight light source, and the like.

It is sectional drawing of white LED which is embodiment of this invention. It is sectional drawing which shows the conventional white LED.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LED element 2 Board | substrate 3 Sealing part 4 Lens 5 Light diffusing agent 10 White LED

Claims (4)

  In a white light emitting diode comprising a light emitting diode that obtains white light from a mixture of light of multiple wavelengths and a condensing lens arranged in the light emitting direction of the light emitting diode, a light diffusing agent is evenly distributed in the lens. A white light-emitting diode having a function of reducing a halo effect by being dispersed and mixed to a weight ratio of several percent or less.   The white light-emitting diode according to claim 1, wherein the lens is an achromatic lens.   The white light emitting diode according to claim 1 or 2, wherein the lens and the sealing portion are formed separately. 2. The light of the plurality of wavelengths includes blue light of a light emitting diode element that emits blue light and yellow light from a YAG phosphor excited by the blue light. The white light emitting diode according to claim 3.

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